The Colorado Rockies' Juan Nicasio and Arizona Diamondbacks' Brandon McCarthy each have a lofty ERA but the two have experienced differing results.

Nicasio will try to stay unbeaten while leading the surging Rockies to a ninth straight win Sunday against the Diamondbacks and the winless McCarthy.

Nicasio (2-0, 5.63 ERA) is one of the pitchers to benefit from Colorado's longest win streak since a 10-game run Sept. 3-12, 2010. The right-hander gave up four runs for the second straight outing Tuesday but picked up the win in an 8-4 victory over the visiting New York Mets.

"It wasn't his sharpest game, but he kept us in the game and gave us a shot," manager Walt Weiss told the team's website.

The Rockies (13-4) improved to 8-0 at Coors Field by holding on for a 4-3 win over Arizona (9-8) on Saturday. Colorado, the only remaining unbeaten team at home, gave up all the runs in the final two innings.

The Rockies have outscored opponents 55-25 during their franchise-best home start. Colorado will try to extend it while recording its first series sweep over Arizona since Sept. 10-12, 2010, at Coors Field.

Nicasio, who is 0-0 with an 8.59 ERA in two career starts versus the Diamondbacks (9-8), has benefited this season from a run support average of 8.4.

McCarthy (0-2, 7.47) has been backed by an average of 6.3 runs, but has been unable to take advantage.

After giving up six runs in each of his first two outings for Arizona, he yielded only a three-run homer to the New York Yankees' Robinson Cano on Tuesday but needed 102 pitches to get through four innings and took the loss in a 4-2 defeat.

"I was just completely out of sync and just kind of not able to do a whole lot," McCarthy told the team's website. "I felt like I was at least still battling, which is kind of good. I just couldn't get right from the (bullpen) all the way through.

"Even after evaluating, I don't know what it is, mechanically, that I was looking for. Just everything was so off."

Before this season, McCarthy was 3-0 with a 1.11 ERA in five starts against NL opponents. He has never faced Colorado and only two Rockies players have faced the right-hander.

Michael Cuddyer is 3 for 17 (.176) with a solo homer and four strikeouts against McCarthy, while Yorvit Torrealba is 3 for 5 with a double.

Cuddyer hit a key solo homer Saturday and Carlos Gonzalez doubled and drove in a run. Gonzalez has played a big role in the winning streak, batting .481 with 10 runs in his last seven.

Paul Goldschmidt and Cody Ross are both 2 for 3 against Nicasio with both of Ross' hits landing for doubles.

The status of veteran first baseman Todd Helton is uncertain. Helton was held out of Saturday's game because of a strained left forearm. He was batting .268 with 10 RBIs in his first 13 games.